Dimethyl sulfoxide: a central player since the dawn of cryobiology, is efficacy balanced by toxicity?

Effects of intracerebroventricular administration of dimethyl sulfoxide on hippocampal electrophysiology in mice

Dimethyl sulfoxide (DMSO) is a commonly used solvent in life sciences due to its excellent ability to dissolve compounds with poor water-solubility. Depending on the applied dose, the variety of DMSO's physiological and biological effects may compromise its suitability as a vehicle molecule. Even low concentrations of DMSO are known to affect neuronal excitability in vitro. As in vivo effects have not been studied extensively, this exploratory study investigated the effects of intracerebroventricular (ICV) administration of different DMSO concentrations on hippocampal electrophysiology in mice. Acute recordings of hippocampal evoked potentials (EPs) and electroencephalography (EEG) were performed before and after ICV injection of a 5 µl DMSO solution, with concentrations ranging from 2.5 % to 100 % DMSO. Solutions containing up to 50 % DMSO had no acute effects on hippocampal electrophysiology. Administration of 75 % and 100 % DMSO was found to alter evoked responses, indicating increased excitability. Our results indicate that DMSO can be used as a vehicle in volumes of 5 µl containing concentrations of up to 50 % without affecting acute hippocampal electrophysiological studies in mice. Higher concentrations should be avoided as these affect neuronal excitability.

Reducing dimethyl sulfoxide content in Jurkat cell formulations suitable for cryopreservation

Cell-based medicinal products (CBMPs) are usually cryopreserved in formulations containing up to 10 % dimethyl sulfoxide (Me2SO) at temperatures below -145 °C. Although Me2SO effectively protects cells during the freezing process, it can be damaging to cells at ambient temperatures and lead to side effects in patients. The aim of this study was to reduce the amount of Me2SO in cryopreservation formulations for an immortalized T cell line (Jurkat cells). A design of experiment (DoE) approach was applied for formulation development using seven different excipients, i.e., Me2SO, trehalose, sorbitol, proline, ectoine, poloxamer 188 (P188) and poly vinyl pyrrolidone 40 (PVP). A DoE model was generated to predict optimal formulations resulting in a high post-thaw viability and a high glass transition temperature of the formulation to allow for frozen storage without the use of liquid nitrogen. Subsequently a stability study was performed with promising lead candidates over three months at storage temperatures of -145 °C, -80 °C, -40 °C. Three benchmark solutions were used, i.e., Cryostor CS10, CryoSOfree as well as 10 % Me2SO in Roswell Park Memorial Institute Medium (RPMI). The excipient affecting the post-thaw viability of Jurkat cells the most was, as expected, Me2SO, which led to increased viabilities at higher concentrations. Most formulations resulted in similar viabilities for cells stored at -145 °C and -80 °C, whereas samples stored at -40 °C did not survive. In general, benchmark formulations resulted in slightly higher viabilities than the tested formulations. Furthermore, cell samples stored at -80 °C were recultivated in cell culture and the viability was assessed after 24h. The cell viability after 24h was much lower compared to the cells analyzed directly post-thaw, indicating that freeze-thaw damages continue to unfold after thawing. In summary, several promising excipients and combinations thereof, e.g., trehalose and PVP, were identified for the cryopreservation of Jurkat cells with reduced concentrations of Me2SO or Me2SO-free cryopreservation. Additionally, storage at -80 °C is possible for the developed formulations.

Water-soluble BODIPY dyes: a novel approach for their sustainable chemistry and applied photonics

The BODIPY family of organic dyes has emerged as a cornerstone in photonics research development, driving innovation and advancement in various fields of high socio-economic interest. However, the majority of BODIPY dyes exhibit hydrophobic characteristics, resulting in poor solubility in water and other hydrophilic solvents. This solubility is paramount for their optimal utilization in a myriad of photonic applications, particularly in the realms of biology and medicine. Furthermore, it facilitates safer and more sustainable manipulation and chemical modification of these expansive dyes. Nevertheless, bestowing BODIPYs with water solubility while preserving their other essential properties, notably their photophysical signatures, poses a significant challenge. In this context, we present a straightforward general chemical modification aimed at converting conventional hydrophobic BODIPYs into highly hydrophilic variants, thus enabling their efficient solubilization in water and other hydrophilic solvents with minimal disruption to the dye's inherent photophysics. The efficacy of this methodology is demonstrated through the synthesis of a number of water-soluble BODIPY dyes featuring diverse substitution patterns. Furthermore, we showcase their utility in a spectrum of photonics-related applications, including in-water BODIPY chemistry and dye-laser technology, and fluorescence microscopy.

Revolutionising Cancer Immunotherapy: Advancements and Prospects in Non-Viral CAR-NK Cell Engineering

The recent advancements in cancer immunotherapy have spotlighted the potential of natural killer (NK) cells, particularly chimeric antigen receptor (CAR)-transduced NK cells. These cells, pivotal in innate immunity, offer a rapid and potent response against cancer cells and pathogens without the need for prior sensitization or recognition of peptide antigens. Although NK cell genetic modification is evolving, the viral transduction method continues to be inefficient and fraught with risks, often resulting in cytotoxic outcomes and the possibility of insertional mutagenesis. Consequently, there has been a surge in the development of non-viral transfection technologies to overcome these challenges in NK cell engineering. Non-viral approaches for CAR-NK cell generation are becoming increasingly essential. Cutting-edge techniques such as trogocytosis, electroporation, lipid nanoparticle (LNP) delivery, clustered regularly interspaced short palindromic repeats-associated protein 9 (CRISPR-Cas9) gene editing and transposons not only enhance the efficiency and safety of CAR-NK cell engineering but also open new avenues for novel therapeutic possibilities. Additionally, the infusion of technologies already successful in CAR T-cell therapy into the CAR-NK paradigm holds immense potential for further advancements. In this review, we present an overview of the potential of NK cells in cancer immunotherapies, as well as non-viral transfection technologies for engineering NK cells.

Allogeneic umbilical cord-derived mesenchymal stromal cells as treatment for systemic lupus erythematosus: a single-centre, open-label, dose-escalation, phase 1 study

BACKGROUND

Patients with systemic lupus erythematosus (SLE) with inadequate responses to standard therapies have unmet therapeutic needs. The immunomodulatory, proangiogenic, and antifibrotic properties of mesenchymal stromal cells support their use in treating patients with SLE. We aimed to assess the safety of a single intravenous infusion of allogeneic umbilical cord-derived mesenchymal stromal cells in patients with severe SLE.

METHODS

This prospective, single-centre, open-label, dose-escalation, Bayesian phase 1 study was done at the Saint-Louis University Hospital (Paris, France). Eligible patients were aged 18-70 years, were diagnosed with SLE according to American College of Rheumatology criteria with positive antinuclear antibodies, had a baseline Safety of Estrogens in Lupus Erythematosus National Assessment-SLE Disease Activity Index (SELENA-SLEDAI) score of 6 or more, and had disease that was refractory to first and second line SLE therapies. Patients were to receive a single intravenous infusion of 1 × 106, 2 × 106, or 4 × 106 umbilical cord-derived mesenchymal stromal cells per kg (manufactured from a single umbilical cord) in cohorts of five patients per dose, starting at 2 × 106 cells per kg. The primary endpoint was the rate of treatment-related severe adverse events (grade ≥3) in the first 10 days after infusion of umbilical cord-derived mesenchymal stromal cells. People with lived experience were involved in study design, patient enrolment, and dissemination of the study findings. This study is registered with ClinicalTrials.gov, NCT03562065, and the EU Clinical Trials Register, EudraCT2017-001400-29.

FINDINGS

From May 14, 2019, to March 6, 2023, 29 patients were screened for eligibility, eight of whom were enrolled in the study. Enrolment was terminated early after inclusion of eight patients and no patients received the 1 × 106 dose of umbilical cord-derived mesenchymal stromal cells. Seven (88%) of eight participants were cisgender women and one (13%) was a cisgender man. The median age was 35 years (range 26-57) and the median SLE disease duration was 12 years (5-19). All patients received at least 2 × 106 cells per kg (range 2 × 106 to 4 × 106). No severe adverse events and three infusion-related adverse events (two grade 1 and one grade 2) occurred in two patients in the first 10 days after infusion. After 12·4 months (range 12-13) of follow-up, no treatment-related severe adverse events and three non-treatment-related severe adverse events occurred in one patient after relapse.

INTERPRETATION

Our results suggest that a single infusion of 2 × 106 cells per kg or 4 × 106 cells per kg of allogeneic umbilical cord-derived mesenchymal stromal cells was safe in patients with severe SLE. Placebo-controlled trials are needed to confirm clinical efficacy and the role of B-cell modifications in clinical benefit.

FUNDING

Fondation du Rein, Alliance Maladies Rares AFM-Téléthon, Direction de la Recherche Clinique et de l'Innovation AP-HP, and ANR eCellFrance.

Flow cytometry reveals constant lymphocyte proportions after long-term cryopreservation of whole blood in TransFix® cell stabilization reagent

Flow cytometry is an important technique for characterization of immune cells, with accurate lymphocyte profiling being essential for clinical diagnostics and research applications. While immediate processing of blood samples is ideal, long-term storage solutions are needed for large-scale studies or settings without immediate access to laboratory facilities. TransFix® is a chemical stabilization solution that allows delayed analysis by preserving cell morphology and surface markers. However, the impact of long-term cryopreservation in TransFix® on lymphocyte integrity remains underexplored. In this study, we evaluated the efficacy of cryopreservation in TransFix® for maintaining the proportions of key lymphocyte subsets, including CD3+ T cells, CD3+CD4+ T helper cells, CD3+CD8+ cytotoxic T cells, CD19+ B cells, and CD16+/CD56+ natural killer cells. Blood samples were cryopreserved in TransFix® for varying time periods, up to 48 months, and compared to fresh samples using flow cytometry. The results show that the proportions of lymphocyte subsets remain stable during cryopreservation for up to 48 months, with no significant differences observed between fresh and cryopreserved samples. This suggests that TransFix® can successfully preserve lymphocyte integrity for long-term storage, providing a reliable option for delayed analysis. These results highlight the usefulness of TransFix® for studies that require extended storage, making it easier to conduct immune monitoring in a wide range of settings.

Comparison of the quality of ovarian tissue cryopreservation by conventional slow cryopreservation and vitrification-a systematic review and meta-analysis

BACKGROUND

Ovarian tissue cryopreservation is increasingly applied in patients undergoing gonadotoxic radiotherapy or chemotherapy treatment or other patients who need to preserve their fertility. However, there is currently limited evidence to know which type of ovarian tissue cryopreservation is better. The advantages and disadvantages of conventional slow cryopreservation and vitrification are still controversial. The purpose of this meta-analysis was to analyze the ovarian tissue quality of ovarian tissue cryopreservation by conventional slow cryopreservation and vitrification.

METHODS

According to the keywords, Pubmed, Embase, and Cochrane Library were searched for studies to January 2024. Studies comparing the follicular viability of conventional slow cryopreservation versus vitrification were assessed for eligibility. The meta-analysis was performed using Stata software (Version 12.0) and Review Manager (Version 5.2).

RESULTS

A total of 18 studies were included in this meta-analysis. The pooled results of the primary outcomes indicated that there was no difference between the two approaches for follicular viability (RR = 0.96, 95% CI: 0.84-1.09, P = 0.520, I2 = 95.8%, Random-effect), the proportion of intact primordial follicles (RR = 1.01, 95% CI: 0.94-1.09, P = 0.778, I2 = 70.6%, Random-effect). The pooled results of the secondary outcomes indicated that there was no difference between the two approaches for the proportion of DNA fragmented follicles (RR = 1.20, 95% CI: 0.94-1.54, P = 0.151, I2 = 0.0%, Fixed-effect), and the proportion of stromal cells (RR = 0.58, 95% CI: 0.20-1.65, P = 0.303, I2 = 99.7%, Random-effect).

CONCLUSIONS

Conventional slow cryopreservation and vitrification appear to provide comparable outcomes. The heterogeneity of the literature prevents us from comparing these two techniques. Further high-quality studies are needed to enhance this statement. This meta-analysis provides limited data which may help clinicians when counselling patients.

Reviving hope: unlocking pancreatic islet immortality by optimizing a trehalose-based cryopreservation media and cell-penetrating peptide

BACKGROUND

Diabetes mellitus remains a pervasive global health concern, urging a deeper exploration of islet transplantation as a potential enduring solution. The efficacy of this therapeutic approach pivots on the precision of cryopreservation techniques, ensuring both the viability and accessibility of pancreatic islets. This study delves into the merits of cryopreserving these islets using the disaccharide trehalose, accompanied by an inventive strategy involving poly L proline (PLP) as a cell-penetrating peptide to overcome the cryoprotectant limitations inherent to trehalose.

METHODS

In our experiments with rat islets, we conducted meticulous viability assessments for fresh and frozen samples. We employed a spectrum of methods, including live/dead staining, insulin/glucagon staining, and measurement of reactive oxygen species (ROS) levels. To gauge functional integrity, we executed glucose-stimulated insulin secretion tests. Subsequently, we transplanted thawed islets into diabetic mice to scrutinize their performance in clinically relevant conditions.

RESULTS

Our study yielded compelling results, affirming the successful cryopreservation of pancreatic islets using trehalose and PLP. Viability, as corroborated through live/dead and insulin/glucagon staining, underscored the sustained preservation of frozen islets. Moreover, these preserved islets exhibited functional integrity by releasing insulin responsively to glucose stimulation. Significantly, upon transplantation into diabetic mice, the thawed islets proficiently restored euglycemia, evidenced by a substantial reduction in fasting blood glucose and an enhanced glucose tolerance.

CONCLUSION

Our findings accentuate the potential of trehalose and PLP as sophisticated cryoprotectants for preserving pancreatic islets. Beyond highlighting viability and functionality, the preserved islets demonstrated a remarkable capacity to restore euglycemia post-transplantation. This research holds promise in addressing the inherent limitations of islet transplantation, particularly in the realm of Type 1 diabetes treatment.

Quantitative and qualitative histological evaluation of different regions of cryopreserved skin derived from red-rumped agouti for obtaining cryobanks

Skin banks are valuable tools for the maintenance of biodiversity. The red-rumped agouti is a wild rodent of ecological importance in South America because it acts as a seed disperser, and skin banks could serve as alternatives to conserve genetic variability. Nevertheless, the most suitable skin region for forming these banks must still be determined to guarantee tissue quality after cryopreservation. We harvested skin tissues from the ear, abdominal, and inguinal regions of red-rumped agouti and evaluated the effects of cryopreservation on the quantitative and qualitative histological parameters of these somatic tissues. All tissues were evaluated for ultrastructure, skin thickness, cell count, number of perinuclear halos, collagen density, proliferative activity, and cellular ability during culture. Cryopreservation altered the thicknesses of the abdominal and inguinal dermises. Cryopreservation did not alter the number of fibroblasts and perinuclear halos in any region. The abdominal region had a higher number of fibroblasts than the other regions. All groups showed increased collagen fibers after cryopreservation, while maintaining a similar proliferative potential. During culture, all regions presented with cell viability above 90 % before and after cryopreservation, and the doubling time was maintained. However, cells from the inguinal and abdominal regions had lower metabolic rates than those from the ear. In summary, the ear skin was found to be the best region for cell recovery. However, abdominal skin has shown positive results and may be an alternative source of somatic cells.

Detecting changes of testicular interstitial cell membranes with a fluorescent probe after incubation and cryopreservation with cryoprotective agents

Membrane alterations are among central factors predetermining cell survival during cryopreservation. In the present research, we tested some serum-/xeno-free cryoprotective compositions including dimethyl sulfoxide (Me2SO) and polymers for their osmotic impact and toxicity towards testicular interstitial cells (ICs). IC survival was determined after their contact with Me2SO, dextran (D40), hydroxyethyl starch (HES), polyethylene glycols (PEG1500 and PEG400), or after cryopreservation and cryoprotective agent (CPA) removal. A ratiometric fluorescent membrane probe 2-(2'-hydroxyphenyl)-5-phenyl-1,3-oxazole (probe O1O) was applied to assess changes in the plasma membrane of ICs. The cell survival study has shown that Me2SO decreased IC survival in a time- and dosage-dependent manner. The CPA decreased the metabolic activity of ICs, thus implying its toxic effect on the living cell as a whole. Using probe O1O, we have demonstrated that the toxic effect also influenced the plasma membrane. IC membranes were not altered after incubation with 0.7 M Me2SO. The presence of D40, HES, or PEGs in such Me2SO containing media resulted in plasma membrane hydration and damage to the membranes of cells incubated with PEGs. Cryopreservation caused pronounced membrane dehydration of the survived ICs even after CPA removal in PEG-containing media and low indicators of IC survival. Interestingly, cryopreservation with the best cryoprotective media supplemented with 0.7 M Me2SO and 100 mg/ml D40 resulted in minimal membrane alterations, thus implying its higher ability to protect membranes during cryopreservation.

Beyond transplants: current and future therapeutic potential of amniotic membrane extract (AME) in ophthalmology

There is no established consensus or standardized method for the preparation of amniotic membrane extract (AME). Consequently, various preparation, preservation, and sterilization techniques have been employed. To obtain AME rich in bioactive components with high therapeutic efficacy, each step of the preparation process is of critical importance. The appropriate procurement of the amniotic membrane minimizes the risk of infection transmission and reduces inter- and intra-donor variability. For the subsequent extraction process, different approaches are utilized due to factors such as laboratory infrastructure variability and the lack of a standardized method. Although lyophilization has recently emerged as a prominent method for the long-term preservation of AME, further investigation is required to assess its impact on the biochemical composition and clinical efficacy of the membrane. In ophthalmology, in vitro, in vivo, and clinical studies indicate that AME supports corneal epithelial regeneration, suppresses inflammation, and is a well-tolerated therapeutic agent. Consequently, further studies are still needed to enhance the effective release of therapeutic components from the amniotic membrane, improve the quality and consistency of AME, and preserve its content over an extended period. Thus, the clinical application of AME-derived products in the form of eye drops will become more widespread in the future.

Fatty Alcohol Membrane Model for Quantifying and Predicting Amphiphilicity

Amphiphilicity is an important property for drug development and self-assembly. This paper introduces a general approach based on a simple fatty alcohol (dodecanol) membrane model that can be used to quantify the amphiphilicity of small molecules that are in good agreement with experimental surface tension data. By applying the model to a systematic series of compounds, it was possible to elucidate the effect of different motifs on amphiphilicity. The results further indicate that amphiphilicity correlates strongly with water-octanol partition coefficients (logP) for the 29 organic molecules examined in the 0 < logP < 4 range. Importantly, the simulation of the model membrane is an order of magnitude faster than a phospholipid membrane (e.g., 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) simulation and offers a simple atomistic approach for quantifying and predicting amphiphilicity of small drug-like molecules that could be used in quantitative structure-activity relationship studies.

Insights on the role of cryoprotectants in enhancing the properties of bioinks required for cryobioprinting of biological constructs

Preservation and long-term storage of readily available cell-laden tissue-engineered products are major challenges in expanding their applications in healthcare. In recent years, there has been increasing interest in the development of off-the-shelf tissue-engineered products using the cryobioprinting approach. Here, bioinks are incorporated with cryoprotective agents (CPAs) to allow the fabrication of cryopreservable tissue constructs. Although this method has shown potential in the fabrication of cryopreservable tissue-engineered products, the impact of the CPAs on the viscoelastic behavior and printability of the bioinks at cryo conditions remains unexplored. In this study, we have evaluated the influence of CPAs such as glycerol and dimethyl sulfoxide (DMSO) on the rheological properties of pre-crosslinked alginate bioinks for cryoprinting applications. DMSO-incorporated bioinks showed a reduction in viscosity and yield stress, while the addition of glycerol improved both the properties due to interactions with the calcium chloride used for pre-crosslinking. Further, tube inversion and printability experiments were performed to identify suitable concentrations and cryobioprinting conditions for bioinks containing CPAs & pre-crosslinked with CaCl2. Finally, based on the printability analysis & cell recovery results, 10% glycerol was used for cryobioprinting and preservation of cell-laden constructs at -80 °C and the viability of cells within the printed structures were evaluated after recovery. Cell viability results indicate that the addition of 10% glycerol to the pre-crosslinked bioink significantly improved cell viability compared to bioinks without CPAs, confirming the suitability of the developed bioink combination to fabricate tissue constructs for on-demand applications.

Synergistic Effect of Polyglycerol and DMSO for Long-Term Cryopreservation of Stichococcus Species

Herein, we present a significant advancement in long-term cryopreservation techniques for microalgae Stichococcus species using a combination of linear polyglycerol (linPG) and dimethyl sulfoxide (DMSO). The technique was tested on three Stichococcus species: Stichococcus bacillaris, Stichococcus deasonii, and Stichococcus minor, which showed long-term viability and recovery rates superior to those when treated with a traditional cryoprotectant only. While DMSO alone enabled high cell recovery rates for all species after 1 week of cryopreservation, the rates for some of them dropped below 50% after 26 weeks of cryopreservation. Treating the cells with a combination of linPG and DMSO raised the recovery rates for all three Stichococcus species to above 92% after long-term cryopreservation. Our findings indicate that linPG in combination with DMSO offers a synergistic and effective solution for maintaining cell integrity and functionality during long-term cryopreservation of microalgae.

Patient-Specific Variability in Interleukin-6 and Myeloperoxidase Responses in Osteoarthritis: Insights from Synthetic Data and Clustering Analysis

Objectives: This study investigated the inflammatory responses of fibroblast-like synoviocytes (FLS) isolated from osteoarthritis (OA) patients, stimulated with lipopolysaccharide (LPS) and interleukin-6 (IL-6). Both experimental and synthetic data were utilised to investigate the variability in IL-6 and myeloperoxidase (MPO) production and its implications for OA pathogenesis. Methods: Synovial biopsies were obtained from OA patients undergoing joint replacement surgery. FLS were isolated, cultured, and stimulated with varying concentrations of LPS and IL-6. The production of IL-6 and MPO was measured using enzyme-linked immunosorbent assays (ELISA). Synthetic data generation techniques expanded the dataset to support comprehensive statistical analyses. Results: The patterns of inflammatory responses revealed distinct patient subgroups, highlighting individual variability. The integration of synthetic data with experimental observations validated their reliability and demonstrated dose-dependent differences in IL-6 and MPO production across patients. Conclusions: The results highlighted the importance of patient-specific factors in OA inflammation and demonstrated the utility of combining experimental and synthetic data to model individual variability. The results support the development of personalised treatment strategies in OA. Future research should include larger patient datasets and an exploration of molecular mechanisms underlying these responses.

Isolation, Expansion, and Characterization of Rat Hair Follicle Stem Cells and Their Secretome: Insights into Wound Healing Potential

Background: Stem cells are capable of self-renewal and differentiation into various specialized cells, making them a potential therapeutic option in regenerative medicine. This study establishes a comprehensive methodology for isolating, culturing, and characterizing rat hair follicle stem cells. Methods and Results: Hair follicles were harvested from Sprague-Dawley rats and subjected to two different isolation techniques. Immunohistochemical analysis and real-time PCR confirm the expression of specific surface markers and genes, validating the cells' identity. Growth kinetics, colony formation units (CFU), and tri-differentiation capacity were also assessed. Additionally, the cells' secretome was analyzed, regarding its content in biofactors with wound healing properties. Conclusions: These findings highlight the potential of these cells as a valuable cell source for skin regeneration applications. They contribute to advancing our understanding of stem cell applications in regenerative medicine and hold promise for therapeutic interventions in various clinical contexts, aligning with broader research on the diverse capabilities of hair follicle stem cells.

Dimethyl-Sulfoxide-Free Cell Cryoprotectant Derived from Amino Acids

With the large-scale applications of cryopreservation technology in the cell therapy fields, traditional permeable cryoprotectants (CPAs) have led to serious issues, such as cell cycle arrest, inhibition of cell proliferation and differentiation, apoptosis, altered gene expression, etc. Development of green, non-toxic cryoprotectants is critically needed. Amino acids could serve as substrates for protein and cellular metabolism and as cryoprotectants with non-toxicity, balancing the intracellular water osmotic pressure. Current research on amino acids as cryoprotectants is hindered by several limitations, including unclear protection mechanisms, cryopreservation methods, and poor efficacy of individual formulations. Therefore, three specific amino acids and derivatives, including l-proline, l-carnitine, and betaine, as cryoprotectants were used for two types of cell cryopreservation. Single-factor experiments were conducted to obtain the optimal concentration range for each of the three amino acid cryoprotectants. On the basis of the key thermophysical parameters, the ability to inhibit ice crystals, and the effect after cryopreservation, multivariate orthogonal experiments were carried out to evaluate the actual effect of the three-component mixed cryoprotectant on cell cryopreservation. In comparison to the gold standard of 10% dimethyl sulfoxide (DMSO) for cell cryopreservation, the mixed cryoprotectant derived from amino acids achieves comparable preservation efficacy at lower concentrations with a convenient application method, which offers guidance for DMSO-free cryoprotectants.

Considerations for manufacturing of cell and gene medicines for clinical development

The global changes from 2001 that elevated substantially modified cell therapies to the definition of "medicinal product" have been the catalyst for the dramatic expansion of the field to its current and future commercial success. Europe was the first to incorporate human somatic cells into drug legislation with the medicines directive of 2001 (2001/83/EC), which led to the development of the term "advanced therapy medicinal products" (ATMPs) to cover all substantially modified products, tissue-engineered products and somatic cells that are not substantially modified but that are used non-homologously. For convenience, I use the term "ATMPs" throughout this review. The transition from "cell therapy" to "cellular medicine" coincided with changes in clinical trial legislation in Europe and, subsequently, across many drug jurisdictions throughout the world. As medicines, there is a clear path through multiple phases of trials and associated requirements for compliance with the good practice standards of drug development, and manufacturability is central to this development.

Cryopreservation of Immune Cells: Recent Progress and Challenges Ahead

Cryopreservation of immune cells is considered as a key enabling technology for adoptive cellular immunotherapy. However, current immune cell cryopreservation technologies face the challenges with poor biocompatibility of cryoprotection materials, low efficiency, and impaired post-thaw function, limiting their clinical translation. This review briefly introduces the adoptive cellular immunotherapy and the approved immune cell-based products, which involve T cells, natural killer cells and etc. The cryodamage mechanisms to these immune cells during cryopreservation process are described, including ice formation related mechanical and osmotic injuries, cryoprotectant induced toxic injuries, and other biochemical injuries. Meanwhile, the recent advances in the cryopreservation medium and freeze-thaw protocol for several representative immune cell type are summarized. Furthermore, the remaining challenges regarding on the cryoprotection materials, freeze-thaw protocol, and post-thaw functionality evaluation of current cryopreservation technologies are discussed. Finally, the future perspectives are proposed toward advancing highly efficient cryopreservation of immune cells.

Ice recrystallization inhibitors enable efficient cryopreservation of induced pluripotent stem cells: A functional and transcriptomic analysis

The successful use of human induced pluripotent stem cells (iPSCs) for research or clinical applications requires the development of robust, efficient, and reproducible cryopreservation protocols. After cryopreservation, the survival rate of iPSCs is suboptimal and cell line-dependent. We assessed the use of ice recrystallization inhibitors (IRIs) for cryopreservation of human iPSCs. A toxicity screening study was performed to assess specific small-molecule carbohydrate-based IRIs and concentrations for further evaluation. Then, a cryopreservation study compared the cryoprotective efficiency of 15 mM IRIs in 5 % or 10 % DMSO-containing solutions and with CryoStor® CS10. Three iPSC lines were cryopreserved as single-cell suspensions in the cryopreservation solutions and post-thaw characteristics, including pluripotency and differential gene expression were assessed. We demonstrate the fitness-for-purpose of 15 mM IRI in 5 % DMSO as an efficient cryoprotective solution for iPSCs in terms of post-thaw recovery, viability, pluripotency, and transcriptomic changes. This mRNA sequencing dataset has the potential to be used for molecular mechanism analysis relating to cryopreservation. Use of IRIs can reduce DMSO concentrations and its associated toxicities, thereby improving the utility, effectiveness, and efficiency of cryopreservation.

Impact of controlled ice nucleation on intracellular dehydration, ice formation and their implications on T cell freeze-thaw viability

Cryopreservation is important in manufacturing of cell therapy products, influencing their safety and effectiveness. During freezing and thawing, intracellular events such as dehydration and ice formation can impact cell viability. In this study, the impact of controlling the ice nucleation temperature on intracellular events and viability were investigated. A model T cell line, Jurkat cells, were evaluated in commercially relevant cryoformulations (2.5 and 5 % v/v DMSO in Plasma-Lyte A) using a cryomicroscopic setup to monitor the dynamic changes cells go through during freeze-thaw as well as a controlled rate freezer to study bulk freeze-thaw. The equilibrium freezing temperatures of the studied formulations and a DMSO/Plasma-Lyte A liquidus curve were determined using DSC. The cryomicroscopic studies revealed that an ice nucleation temperature of -6°C, close to the equilibrium freezing temperatures of cryoformulations, led to more intracellular dehydration and less intracellular ice formation during freezing compared to either a lower ice nucleation temperature (-10 °C) or uncontrolled ice nucleation. The cell membrane integrity and post thaw viability in bulk cryopreservation consistently demonstrated the advantage of the higher ice nucleation temperature, and the correlation between the cellular events and cell viability.

Cellular resiliency and survival of Neuro-2a cells under extreme stress

Stressors such as hypoxia, hypothermia, and acute toxicity often result in widespread cell death. This study investigated the outcomes of Neuro-2a (N2a; mouse neuroblastoma) cells following a cryogenic storage failure that exposed them to a combination of these stressors over a period of approximately 24-30 hours. Remarkably, a small fraction of the cells survived the event, underwent a period of dormancy, and eventually recovered to a healthy state. To understand the underlying resilience mechanisms, we created a model to replicate the dewar failure event and examined changes in phenotype, transcriptomics, proteomics, and mitochondrial activity of the surviving cells during recovery. We found that the surviving cells initially displayed a stressed morphology with irregular membranes and a clustered apperance. They showed an increased expression of proteins related to DNA repair and chromatin modification pathways as well as heightened mitochondrial function shortly after the stress event. As recovery progressed, the stress-responsive pathways, mitochondrial activity, and growth rates normalized toward that of healthy controls, indicating a return to a stable baseline state. These findings suggest that an initial robust energetic state supports key stress-responsive and repair pathways at the early stages of recovery, facilitating cell survival and resiliency after extreme stress. This work provides valuable insights into cellular resilience mechanisms with potential implications for improving cell preservation and recovery in biomedical applications and developing therapeutic strategies for conditions involving cell damage and stress.

Engineering a Microfluidic Platform to Cryopreserve Stem Cells: A DMSO-Free Sustainable Approach

Human adipose-derived stem cells (hASCs) are cryopreserved traditionally using dimethyl sulfoxide (DMSO) as the cryoprotectant agent. DMSO penetrates cell membranes and prevents cellular damage during cryopreservation. However, DMSO is not inert to cells, inducing cytotoxic effects by causing mitochondrial dysfunction, reduced cell proliferation, and impaired hASCs transplantation. Additionally, large-scale production of DMSO and contamination can adversely impact the environment. A sustainable, green alternative to DMSO is trehalose, a natural disaccharide cryoprotectant agent that does not pose any risk of cytotoxicity. However, the cellular permeability of trehalose is less compared to DMSO. Here, a microfluidic chip is developed for the intracellular delivery of trehalose in hASCs. The chip is designed for mechanoporation, which creates transient pores in cell membranes by mechanical deformation. Mechanoporation allows the sparingly permeable trehalose to be internalized within the cell cytosol. The amount of trehalose delivered intracellularly is quantified and optimized based on cellular compatibility and functionality. Furthermore, whole-transcriptome sequencing confirms that less than 1% of all target genes display at least a twofold change in expression when cells are passed through the chip compared to untreated cells. Overall, the results confirm the feasibility and effectiveness of using this microfluidic chip for DMSO-free cryopreservation of hASCs.

Structural investigation, computational analysis, and theoretical cryoprotectant approach of antifreeze protein type IV mutants

Antifreeze proteins (AFPs) have unique features to sustain life in sub-zero environments due to ice recrystallization inhibition (IRI) and thermal hysteresis (TH). AFPs are in demand as agents in cryopreservation, but some antifreeze proteins have low levels of activity. This research aims to improve the cryopreservation activity of an AFPIV. In this in silico study, the helical peptide afp1m from an Antarctic yeast AFP was modeled into a sculpin AFPIV, to replace each of its four α-helices in turn, using various computational tools. Additionally, a new linker between the first two helices of AFPIV was designed, based on a flounder AFPI, to boost the ice interaction activity of the mutants. Bioinformatics tools such as ExPASy Prot-Param, Pep-Wheel, SOPMA, GOR IV, Swiss-Model, Phyre2, MODFOLD, MolPropity, and ProQ were used to validate and analyze the structural and functional properties of the model proteins. Furthermore, to evaluate the AFP/ice interaction, molecular dynamics (MD) simulations were executed for 20, 100, and 500 ns at various temperatures using GROMACS software. The primary, secondary, and 3D modeling analysis showed the best model for a redesigned antifreeze protein (AFP1mb, with afp1m in place of the fourth AFPIV helix) with a QMEAN (Swiss-Model) Z score value of 0.36, a confidence of 99.5%, a coverage score of 22%, and a p value of 0.01. The results of the MD simulations illustrated that AFP1mb had more rigidity and better ice interactions as a potential cryoprotectant than the other models; it also displayed enhanced activity in limiting ice growth at different temperatures.

Orthobiologic Products: Preservation Options for Orthopedic Research and Clinical Applications

The biological products used in orthopedics include musculoskeletal allografts-such as bones, tendons, ligaments, and cartilage-as well as biological therapies. Musculoskeletal allografts support the body's healing process by utilizing preserved and sterilized donor tissue. These allografts are becoming increasingly common in surgical practice, allowing patients to avoid more invasive procedures and the risks associated with donor site morbidity. Bone grafting is one of the most frequently used procedures in orthopedics and traumatology. Biologic approaches aim to improve clinical outcomes by enhancing the body's natural healing capacity and reducing inflammation. They serve as an alternative to surgical interventions. While preliminary results from animal studies and small-scale clinical trials have been promising, the field of biologics still lacks robust clinical evidence supporting their efficacy. Biological therapies include PRP (platelet-rich plasma), mesenchymal stem cells (MSCs)/stromal cells/progenitor cells, bone marrow stem/stromal cells (BMSCs), adipose stem/stromal cells/progenitor cells (ASCs), cord blood (CB), and extracellular vesicles (EVs), including exosomes. The proper preservation and storage of these cellular therapies are essential for future use. Preservation techniques include cryopreservation, vitrification, lyophilization, and the use of cryoprotective agents (CPAs). The most commonly used CPA is DMSO (dimethyl sulfoxide). The highest success rates and post-thaw viability have been achieved by preserving PRP with a rate-controlled freezer using 6% DMSO and storing other cellular treatments using a rate-controlled freezer with 5% or 10% DMSO as the CPA. Extracellular vesicles (EVs) have shown the best results when lyophilized with 50 mM or 4% trehalose to prevent aggregation and stored at room temperature.

Longevity biotechnology: bridging AI, biomarkers, geroscience and clinical applications for healthy longevity

The recent unprecedented progress in ageing research and drug discovery brings together fundamental research and clinical applications to advance the goal of promoting healthy longevity in the human population. We, from the gathering at the Aging Research and Drug Discovery Meeting in 2023, summarised the latest developments in healthspan biotechnology, with a particular emphasis on artificial intelligence (AI), biomarkers and clocks, geroscience, and clinical trials and interventions for healthy longevity. Moreover, we provide an overview of academic research and the biotech industry focused on targeting ageing as the root of age-related diseases to combat multimorbidity and extend healthspan. We propose that the integration of generative AI, cutting-edge biological technology, and longevity medicine is essential for extending the productive and healthy human lifespan.

Comparison of Cryopreservation Media for Mesenchymal Stem Cell Spheroids

Multipotent mesenchymal stromal/stem cell (MSC) spheroids generated in three-dimensional culture are of considerable interest as a novel therapeutic tool for regenerative medicine. However, the lack of reliable methods for storing MSC spheroids represents a significant roadblock to their successful use in the clinic. An ideal storage medium for MSC spheroids should function as both a vehicle for delivery and a cryoprotectant during storage of spheroids for use at a later time. In this study, we compared the outcomes after subjecting MSC spheroids to a freeze/thaw cycle in three Good Manufacturing Practices-grade cryopreservation media, CryoStor10 (CS10), Stem-Cellbanker (SCB), and Recovery Cell Culture Freezing Media (RFM) or conventional freezing medium (CM) (CM, Dulbecco's modified Eagle's medium containing 20% fetal bovine serum and 10% dimethyl sulfoxide) as a control for 2 months. The endpoints tested were viability, morphology, and expression of stem cell markers and other relevant genes. The results of LIVE/DEAD™ assays and annexin V/propidium iodide staining suggested that viability was relatively higher after one freeze/thaw cycle in CS10 or SCB than after freeze/thaw in CM or RFM. Furthermore, the relative "stemness" and expression of MSC markers were similar with or without freeze/thaw in CS10. Scanning electron microscopy also indicated that the surface morphology of MSC spheroids was well preserved after cryopreservation in CS10. Thus, even though it was tested for a short-term period, we suggest that CS10, which has been approved for clinical use by the U.S. Food and Drug Association, is a promising cryopreservation medium that would facilitate the development of MSC spheroids for future clinical use.

The effect of DMSO on Saccharomyces cerevisiae yeast with different energy metabolism and antioxidant status

We studied the effect of dimethyl sulfoxide (DMSO) on the biochemical and physiological parameters of S. cerevisiae yeast cells with varied energy metabolism and antioxidant status. The wild-type cells of varied genetic backgrounds and their isogenic mutants with impaired antioxidant defences (Δsod mutants) or response to environmental stress (ESR) (Δmsn2, Δmsn4 and double Δmsn2msn4 mutants) were used. Short-term exposure to DMSO even at a wide range of concentrations (2-20%) had little effect on the metabolic activity of the yeast cells and the stability of their cell membranes, but induced free radicals production and clearly altered their proliferative activity. Cells of the Δsod1 mutant showed greater sensitivity to DMSO in these conditions. DMSO at concentrations from 4 to 10-14% (depending on the strain and genetic background) activated the ESR programme. The effects of long-term exposure to DMSO were mainly depended on the type of energy metabolism and antioxidant system efficiency. Yeast cells with reduced antioxidant system efficiency and/or aerobic respiration were more susceptible to the toxic effects of DMSO than cells with a wild-type phenotype and respiro-fermentative or fully fermentative metabolism. These studies suggest a key role of stress response programs in both the processes of cell adaptation to small doses of this xenobiotic and the processes related to its toxicity resulting from large doses or chronic exposure to DMSO.

Mesenchymal stem cell cryopreservation with cavitation-mediated trehalose treatment

Dimethylsulfoxide (DMSO) has conventionally been used for cell cryopreservation both in research and in clinical applications, but has long-term cytotoxic effects. Trehalose, a natural disaccharide, has been proposed as a non-toxic cryoprotectant. However, the lack of specific cell membrane transporter receptors inhibits transmembrane transport and severely limits its cryoprotective capability. This research presents a method to successfully deliver trehalose into mesenchymal stem cells (MSCs) using ultrasound in the presence of microbubbles. The optimised trehalose concentration was shown to be able to not only preserve membrane integrity and cell viability but also the multipotency of MSCs, which are essential for stem cell therapy. Confocal imaging revealed that rhodamine-labelled trehalose was transported into cells rather than simply attached to the membrane. Additionally, the membranes were successfully preserved in lyophilised cells. This study demonstrates that ultrasonication with microbubbles facilitated trehalose delivery, offering promising cryoprotective capability without the cytotoxicity associated with DMSO-based methods.

Cryopreserving the intact intervertebral disc without compromising viability

Background

Tissue cryopreservation requires saturation of the structure with cryoprotectants (CPAs) that are also toxic to cells within a short timeframe unless frozen. The race between CPA delivery and cell death is the main barrier to realizing transplantation banks that can indefinitely preserve tissues and organs. Unrealistic cost and urgency leaves less life-threatening ailments unable to capitalize on traditional organ transplantation systems that immediately match and transport unfrozen organs. For instance, human intervertebral discs (IVD) could be transplanted to treat back pain or used as ex vivo models for studying regenerative therapies, but both face logistical hurdles in organ acquisition and transport. Here we aimed to overcome those challenges by cryopreserving intact IVDs using compressive loading and swelling to accelerate CPA delivery.

Methods

CPAs were tested on bovine nucleus pulposus cells to determine the least cytotoxic solution. Capitalizing on our CPAs Computed Tomography (CT) contrast enhancement, we imaged and quantified saturation time in intact bovine IVDs under different conditions in a bioreactor. Finally, the entire protocol was tested, including 1 week of frozen storage, to confirm tissue viability in multiple IVD regions after thawing.

Results

Results showed cryopreserving medium containing dimethyl sulfoxide and ethylene glycol gave over 7.5 h before cytotoxicity. While non-loaded IVDs required over 3 days to fully saturate, a dynamic loading protocol followed by CPA addition and free-swelling decreased saturation time to <5 h. After cryopreserving IVDs for 1 week with the optimized CPA and permeation method, all IVD regions had 85% cell viability, not significantly different from fresh unfrozen controls.

Conclusions

This study created a novel solution to a roadblock in IVD research and development. Using post-compression swelling CPA can be delivered to an intact IVD over 20× more quickly than previous methods, enabling cryopreservation of the IVD with no detectable loss in cell viability.

Reassessing Long-Term Cryopreservation Strategies for Improved Quality, Safety, and Clinical Use of Allogeneic Dermal Progenitor Cells

In regenerative medicine, ongoing advancements in cell culture techniques, including isolation, expansion, banking, and transport, are crucial for clinical success. Cryopreservation ensures off-the-freezer availability of living cells, enabling long-term storage and transport. Customizing cryopreservation techniques and cryoprotective agents (CPAs) for specific cell types is crucial for cell source quality, sustainability, safety, and therapeutic intervention efficiency. As regenerative medicine progresses, it becomes imperative that the scientific community and industry provide a comprehensive, cell-specific landscape of available and effective cryopreservation techniques, preventing trial-and-error approaches and unlocking the full potential of cell-based therapies. Open-sharing data could lead to safer, more efficient cell therapies and treatments. Two decades of dermal progenitor cell use for burn wound treatment and Good Manufacturing Practice-compliant technology transfers have highlighted the need for further cryopreservation optimization in manufacturing workflows. In this paper, we present experimental data assessing 5 different cryopreservation formulae for long-term storage of clinical-grade FE002 primary progenitor fibroblasts, emphasizing the crucial difference between DMSO-based and DMSO-free CPAs. Our findings suggest that CryoOx, a DMSO-free CPA, is a promising alternative yielding cell viability similar to that of established commercial CPAs. This research highlights the importance of secure, robust, and efficient cryopreservation techniques in cell banking for maximizing quality, ensuring patient safety, and advancing regenerative medicine.

Cell freezing and the biology of inexorability: on cryoprotectants and chemical time

What can't freezing hold still? This article surveys the history of substances used to protect cells and organisms from freezing damage, known as cryoprotectants. Dimethyl sulfoxide (DMSO) has since 1959 been the most widely used of these agents in cryopreservation. Here, its evolution from pulp and paper waste byproduct to wonder drug to all-but-invisible routine element of freezing protocols is used to trace the direct arc from protection to toxicity in theories of how and why cryoprotectants work, from the 1960s to today. The power of these agents to simultaneously protect and degrade is shown to reside in manipulation of chemical time via hydrogen bonding and electron exchange, thereby reframing freezing as a highly active and transformational process. Countering long-held assumptions about cryopreservation as an operation of stasis after which the thawed entity is the same as it was before, this article details recent demonstrations of effects of cryoprotectant exposure that are nonlethal but nonetheless profoundly impactful within scientific and therapeutic practices that depend on freezing infrastructures. Understanding the operationalization of chemical time in the case of cryoprotectants is broadly relevant to other modern technologies dedicated to shifting how material things exist and persist in human historical time.

Biomaterial-enhanced treg cell immunotherapy: A promising approach for transplant medicine and autoimmune disease treatment

Regulatory T cells (Tregs) are crucial for preserving tolerance in the body, rendering Treg immunotherapy a promising treatment option for both organ transplants and autoimmune diseases. Presently, organ transplant recipients must undergo lifelong immunosuppression to prevent allograft rejection, while autoimmune disorders lack definitive cures. In the last years, there has been notable advancement in comprehending the biology of both antigen-specific and polyclonal Tregs. Clinical trials involving Tregs have demonstrated their safety and effectiveness. To maximize the efficacy of Treg immunotherapy, it is essential for these cells to migrate to specific target tissues, maintain stability within local organs, bolster their suppressive capabilities, and ensure their intended function's longevity. In pursuit of these goals, the utilization of biomaterials emerges as an attractive supportive strategy for Treg immunotherapy in addressing these challenges. As a result, the prospect of employing biomaterial-enhanced Treg immunotherapy holds tremendous promise as a treatment option for organ transplant recipients and individuals grappling with autoimmune diseases in the near future. This paper introduces strategies based on biomaterial-assisted Treg immunotherapy to enhance transplant medicine and autoimmune treatments.

Monarch butterfly conservation through male germplasm cryopreservation

Monarch butterfly (Danaus plexippus L.) populations have declined in North America. The International Union for Conservation of Nature (IUCN) recently classified the species as endangered, sparking public concern and conservation efforts. Our approach to conservation is through cryopreservation of germinal cells and tissue. The goal of this study was to develop a cryopreservation protocol for monarch spermatozoa to ensure successful long-term storage. Cryopreserved sperm cells would provide a reserve of monarch germplasm, which could be utilized in the event of population loss. In this study, sperm cell bundles collected from male monarch butterflies were cryopreserved in a cryoprotective medium and stored in liquid nitrogen. To determine the post-cryopreservation sperm cell viability, a subsample of preserved sperm bundles were thawed rapidly, and their viability was qualified using a sperm live/dead stain. We are presenting a protocol to preserve and store genetic material and viable sperm bundles of the monarch butterfly. To date, this is the first report of successful cryopreservation of monarch germplasm which sets the foundation for cryostorage and could be extensible to other vulnerable lepidopterans.

CellShip: An Ambient Temperature Transport and Short-Term Storage Medium for Mammalian Cell Cultures

Cell culture is a critical platform for numerous research and industrial processes. However, methods for transporting cells are largely limited to cryopreservation, which is logistically challenging, requires the use of potentially cytotoxic cryopreservatives, and can result in poor cell recovery. Development of a transport media that can be used at ambient temperatures would alleviate these issues. In this study, we describe a novel transportation medium for mammalian cells. Five commonly used cell lines, (HEK293, CHO, HepG2, K562, and Jurkat) were successfully shipped and stored for a minimum of 72 hours and up to 96 hours at ambient temperature, after which, cells were recovered into standard culture conditions. Viability (%) and cell numbers, were examined, before, following the transport/storage period and following the recovery period. In all experiments, cell numbers returned to pretransport/storage concentration within 24-48 hours recovery. Imaging data indicated that HepG2 cells were fully adherent and had established typical growth morphology following 48 hours recovery, which was not seen in cells recovered from cryopreservation. Following recovery, Jurkat cells that had been subjected to a 96 hours transport/storage period, demonstrated a 1.93-fold increase compared with the starting cell number with >95% cell viability. We conclude that CellShip® may represent a viable method for the transportation of mammalian cells for multiple downstream applications in the Life Sciences research sector.

Mesenchymal stromal cells derived from various tissues: Biological, clinical and cryopreservation aspects: Update from 2015 review

Mesenchymal stromal cells (MSCs) have become one of the most investigated and applied cells for cellular therapy and regenerative medicine. In this update of our review published in 2015, we show that studies continue to abound regarding the characterization of MSCs to distinguish them from other similar cell types, the discovery of new tissue sources of MSCs, and the confirmation of their properties and functions that render them suitable as a therapeutic. Because cryopreservation is widely recognized as the only technology that would enable the on-demand availability of MSCs, here we show that although the traditional method of cryopreserving cells by slow cooling in the presence of 10% dimethyl sulfoxide (Me2SO) continues to be used by many, several novel MSC cryopreservation approaches have emerged. As in our previous review, we conclude from these recent reports that viable and functional MSCs from diverse tissues can be recovered after cryopreservation using a variety of cryoprotectants, freezing protocols, storage temperatures, and periods of storage. We also show that for logistical reasons there are now more studies devoted to the cryopreservation of tissues from which MSCs are derived. A new topic included in this review covers the application in COVID-19 of MSCs arising from their immunomodulatory and antiviral properties. Due to the inherent heterogeneity in MSC populations from different sources there is still no standardized procedure for their isolation, identification, functional characterization, cryopreservation, and route of administration, and not likely to be a "one-size-fits-all" approach in their applications in cell-based therapy and regenerative medicine.

Optimization of Culture Medium for the Production of an Exopolysaccharide (p-CY02) with Cryoprotective Activity by Pseudoalteromonas sp. RosPo-2 from the Antarctic Sea

When cells are exposed to freezing temperatures, high concentrations of cryoprotective agents (CPA) prevent ice crystal formation, thus enhancing cell survival. However, high concentrations of CPAs can also cause cell toxicity. Exopolysaccharides (EPSs) from polar marine environments exhibit lower toxicity and display effects similar to traditional CPA. In this study, we sought to address these issues by i) selecting strains that produce EPS with novel cryoprotective activity, and ii) optimizing culture conditions for EPS production. Sixty-six bacteria producing mucous substances were isolated from the Ross Sea (Antarctic Ocean) using solid marine agar plates. Among them, Pseudoalteromonas sp. RosPo-2 was ultimately selected based on the rheological properties of the produced EPS (p-CY02). Cryoprotective activity experiments demonstrated that p-CY02 exhibited significantly cryoprotective activity at a concentration of 0.8% (w/v) on mammalian cells (HaCaT). This activity was further improved when combined with various concentrations of dimethyl sulfoxide (DMSO) compared to using DMSO alone. Moreover, the survival rate of HaCaT cells treated with 5% (v/v) DMSO and 0.8% (w/v) p-CY02 was measured at 87.9 ± 2.8% after freezing treatment. This suggests that p-CY02 may be developed as a more effective, less toxic, and novel non-permeating CPA. To enhance the production of EPS with cryoprotective activity, Response Surface Methodology (RSM) was implemented, resulting in a 1.64-fold increase in production of EPS with cryoprotective activity.

Dimethyl Sulfoxide (DMSO) as a Potential Source of Interference in Research Related to Sulfur Metabolism-A Preliminary Study

Dimethyl sulfoxide (DMSO), an organosulfur compound, is widely used as the gold standard solvent in biological research. It is used in cell culture experiments and as a component of formulations in in vivo studies. Unfortunately, parameters related to sulfur metabolism are often not taken into account when using DMSO. Therefore, in this work we aim to show that the addition of DMSO to the culture medium (even in amounts commonly considered acceptable) alters some parameters of sulfur metabolism. For this study, we used three cell lines: a commercially available Caco-2 line (HTB-37, ATCC) and two lines created as part of our early studies (likewise previously described in the literature) to investigate the anomalies of sulfur metabolism in mucopolysaccharidosis. As the negative effects of DMSO on the cell membrane are well known, additional experiments with the partial loading of DMSO into polymerosomes (poly(ethylene glycol) methyl ether-block-poly(lactide-co-glycolide), PEG-PLGA) were performed to eliminate these potentially disruptive effects. The results show that DMSO is a source of interference in studies related to sulfur metabolism and that there are not just simple effects that can be corrected in the final result by subtracting control values, since complex synergisms are also observed.

Modulation of bacterial membranes and cellular macromolecules by dimethyl sulfoxide: A dose-dependent study providing novel insights

Using Escherichia coli as a model, this manuscript delves into the intricate interactions between dimethyl sulfoxide (DMSO) and membranes, cellular macromolecules, and the effects on various aspects of bacterial physiology. Given DMSO's wide-ranging use as a solvent in microbiology, we investigate the impacts of both non-growth inhibitory (1.0 % and 2.5 % v/v) and slightly growth-inhibitory (5.0 % v/v) concentrations of DMSO. The results demonstrate that DMSO causes alterations in bacterial membrane potential, influences the electrochemical characteristics of the cell surface, and exerts substantial effects on the composition and structure of cellular biomolecules. Genome-wide gene expression data from DMSO-treated E. coli was used to further investigate and bolster the results. The findings of this study provide valuable insights into the complex relationship between DMSO and biological systems, with potential implications in drug delivery and cellular manipulation. However, it is essential to exercise caution when utilizing DMSO to enhance the solubility and delivery of bioactive compounds, as even at low concentrations, DMSO exerts non-inert effects on cellular macromolecules and processes.

Selective Targeting of Regulated Rhabdomyosarcoma Cells by Trinuclear Ruthenium(II)-Arene Complexes

The use of benzimidazole-based trinuclear ruthenium(II)-arene complexes (1-3) to selectively target the rare cancer rhabdomyosarcoma is reported. Preliminary cytotoxic evaluations of the ruthenium complexes in an eight-cancer cell line panel revealed enhanced, selective cytotoxicity toward rhabdomyosarcoma cells (RMS). The trinuclear complex 1 was noted to show superior short- and long-term cytotoxicity in RMS cell lines and enhanced selectivity relative to cisplatin. Remarkably, 1 inhibits the migration of metastatic RMS cells and maintains superior activity in a 3D multicellular spheroid model in comparison to that of the clinically used cisplatin. Mechanistic insights reveal that 1 effectively induces genomic DNA damage, initiates autophagy, and prompts the intrinsic and extrinsic apoptotic pathways in RMS cells. To the best of our knowledge, 1 is the first trinuclear ruthenium(II) arene complex to selectively kill RMS cells in 2D and 3D cell cultures.

Pros and Cons of Cryopreserving Allogeneic Stem Cell Products

The COVID-19 pandemic has precipitously changed the practice of transplanting fresh allografts. The safety measures adopted during the pandemic prompted the near-universal graft cryopreservation. However, the influence of cryopreserving allogeneic grafts on long-term transplant outcomes has emerged only in the most recent literature. In this review, the basic principles of cell cryopreservation are revised and the effects of cryopreservation on the different graft components are carefully reexamined. Finally, a literature revision on studies comparing transplant outcomes in patients receiving cryopreserved and fresh grafts is illustrated.

Investigating the cryoprotective efficacy of fructans in mammalian cell systems via a structure-functional perspective

Fructans have long been known with their role in protecting organisms against various stress factors due to their ability to induce controlled dehydration and support membrane stability. Considering the vital importance of such features in cryo-technologies, this study aimed to explore the cryoprotective efficacy of fructans in mammalian cell systems where structurally different fructan polymers were examined on in vitro cell models derived from organs such as the liver, frequently used in transplantation, osteoblast, and cord cells, commonly employed in cell banking, as well as human seminal fluids that are of vital importance in assisted reproductive technology. To gain insights into the fructan/membrane interplay, structural differences were linked to rheological properties as well as to lipid membrane interactions where both fluorescein leakage from unilamellar liposomes and membrane integrity of osteoblast cells were monitored. High survival rates obtained with human endothelial, osteoblast and liver cells for up to two months clearly showed that fructans could be considered as effective non-permeating cryoprotectants, especially for extended periods of cryopreservation. In trials with human seminal fluid, short chained levan in combination with human serum albumin and glycerol proved very effective in preserving semen samples across multiple patients without any morphological abnormalities.

Development of a Me2SO-free cryopreservation medium and its long-term cryoprotection on the CAR-NK cells

Cryopreservation is a crucial step in the supply process of off-the-shelf chimeric antigen receptor engineered natural killer (CAR-NK) cell products. Concerns have been raised over the clinical application of dimethyl sulfoxide (Me2SO) due to the potential for adverse reactions following infusion and limited cell-specific cytotoxic effects if misapplied. In this study, we developed a Me2SO-free cryopreservation medium specifically tailored for CAR-NK cells to address this limitation. The cryopreservation medium was formulated using human serum albumin (HSA) and glycerol as the base components. Following initial screening of seven clinically-compatible solutions, four with cryoprotective properties were identified. These were combined and optimized into a single formulation: IF-M. The viability, phenotype, and function of CAR-NK cells were evaluated after short-term and long-term cryopreservation to assess the effectiveness of IF-M, with Me2SO serving as the control group. The viability and recovery of CAR-NK cells in the IF-M group were significantly higher than those in the Me2SO group within 90 days of cryopreservation. Moreover, after 1 year of cryopreservation the cytotoxic capacity of CAR-NK cells cryopreserved with IF-M was comparable to that of fresh CAR-NK cells and significantly superior to that of CAR-NK cells cryopreserved in Me2SO. The CD107a expression intensity of CAR-NK cells in IF-M group was significantly higher than that of Me2SO group. No statistical differences were observed in other indicators under different cryopreservation times. These results underscore the robustness of IF-M as a suitable replacement for traditional Me2SO-based cryopreservation medium for the long-term cryopreservation and clinical application of off-the-shelf CAR-NK cells.

An important detail that is still not clear in amniotic membrane applications: How do we store the amniotic membrane best?

The use of fresh amniotic membrane (AM) is not a viable option, as it has many disadvantages. Preserving the AM reduces the risk of cross-infection and maintains its effectiveness for a long time. In order to maximize the therapeutic effects of the AM, the basic need is to preserve its vitality and the bioactive molecules it contains. However, the effect of preservation procedures on cell viability and growth factors is a still matter of debate. Optimum preservation method is expected to be cost-effective, easily-accessible, and most importantly, to preserve the effectiveness of the tissue for the longest time. However, each preservation technique has its advantages and disadvantages over the other, and each one compromises the vitality and bioactive molecules of the tissue to some extent. Therefore, the best method of preservation is still controversial, and the question of 'how to preserve the AM best?' has not yet been definitively answered.

Successful expansion and cryopreservation of human natural killer cell line NK-92 for clinical manufacturing

Natural killer (NK) cells have recently shown renewed promise as therapeutic cells for use in treating hematologic cancer indications. Despite this promise, NK cell manufacturing workflows remain largely manual, open, and disconnected, and depend on feeders, as well as outdated unit operations or processes, often utilizing research-grade reagents. Successful scale-up of NK cells critically depends on the availability and performance of nutrient-rich expansion media and cryopreservation conditions that are conducive to high cell viability and recovery post-thaw. In this paper we used Cytiva hardware and media to expand the NK92 cell line in a model process that is suitable for GMP and clinical manufacturing of NK cells. We tested a range of cryopreservation factors including cooling rate, a range of DMSO-containing and DMSO-free cryoprotectants, ice nucleation, and cell density. Higher post-thaw recovery was seen in cryobags over cryovials cooled in identical conditions, and cooling rates of 1°C/min or 2°C/min optimal for cryopreservation in DMSO-containing and DMSO-free cryoprotectants respectively. Higher cell densities of 5x107 cells/ml gave higher post-thaw viability than those cryopreserved at either 1x106 or 5x106 cells/ml. This enabled us to automate, close and connect unit operations within the workflow while demonstrating superior expansion and cryopreservation of NK92 cells. Cellular outputs and performance were conducive to clinical dosing regimens, serving as a proof-of-concept for future clinical and commercial manufacturing.

APOB100 transgenic mice exemplify how the systemic circulation content may affect the retina without altering retinal cholesterol input

Apolipoprotein B (APOB) is a constituent of unique lipoprotein particles (LPPs) produced in the retinal pigment epithelium (RPE), which separates the neural retina from Bruch's membrane (BrM) and choroidal circulation. These LPPs accumulate with age in BrM and contribute to the development of age-related macular degeneration, a major blinding disease. The APOB100 transgenic expression in mice, which unlike humans lack the full-length APOB100, leads to lipid deposits in BrM. Herein, we further characterized APOB100 transgenic mice. We imaged mouse retina in vivo and assessed chorioretinal lipid distribution, retinal sterol levels, retinal cholesterol input, and serum content as well as tracked indocyanine green-bound LPPs in mouse plasma and retina after an intraperitoneal injection. Retinal function and differentially expressed proteins were also investigated. APOB100 transgenic mice had increased serum LDL content and an additional higher density HDL subpopulation; their retinal cholesterol levels (initially decreased) became normal with age. The LPP cycling between the RPE and choroidal circulation was increased. Yet, LPP trafficking from the RPE to the neural retina was limited, and total retinal cholesterol input did not change. There were lipid deposits in the RPE and BrM, and retinal function was impaired. Retinal proteomics provided mechanistic insights. Collectively, our data suggested that the serum LDL/HDL ratio may not affect retinal pathways of cholesterol input as serum LPP load is mainly handled by the RPE, which offloads LPP excess to the choroidal circulation rather than neural retina. Different HDL subpopulations should be considered in studies linking serum LPPs and age-related macular degeneration.

Cryopreservation of human cerebral microvascular endothelial cells with glycerol

The cryopreservation of human cerebral microvascular endothelial cells (hCMEC) has facilitated their commercial availability for research studying the blood-brain barrier. The currently employed cryopreservation protocol uses 10% dimethyl sulfoxide (Me2SO) in cell medium, or 5% Me2SO in 95% fetal bovine serum (FBS) as cryoprotective agents (CPAs). However, Me2SO is toxic to cells and FBS is animal-derived and not chemically defined, so reducing the concentrations of these components is desirable. Recently, we showed that cryopreserving hCMEC in cell medium with 5% Me2SO and 6% hydroxyethyl starch (HES) results in over 90% post-thaw cell viability. This previous work was performed using an interrupted slow cooling (graded freezing) approach followed by SYTO13/GelRed staining to assay for membrane integrity. In this paper, we repeated graded freezing of hCMEC in cell medium containing 5% Me2SO and 6% HES, but this time using Calcein AM/propidium iodide staining to ensure that the stain is an equivalent alternative to SYTO13/GelRed for assessment of cell viability, and that results are comparable to those previously published. Next, using graded freezing experiments and Calcein AM/propidium iodide staining, we examined the effectiveness of non-toxic glycerol as a CPA at different concentrations, loading times, and cooling rates. The cryobiological response of hCMEC was used to develop a protocol that optimizes both the permeating and non-permeating capabilities of glycerol. HCMEC in cell medium loaded with 10% glycerol for 1 h at room temperature, ice nucleated at -5 °C and held for 3 min, and then cooled at -1 °C/min to -30 °C before plunging into liquid nitrogen had post-thaw viability of 87.7% ± 1.8%. Matrigel tube formation assay and immunocytochemical staining of junction protein ZO-1 were carried out on post-thaw hCMEC to ensure that the cryopreserved cells were viable and functional, in addition to being membrane-intact.

Improved Cryopreservation of Human Induced Pluripotent Stem Cell (iPSC) and iPSC-derived Neurons Using Ice-Recrystallization Inhibitors

Human induced pluripotent stem cells (iPSCs) and iPSC-derived neurons (iPSC-Ns) represent a differentiated modality toward developing novel cell-based therapies for regenerative medicine. However, the successful application of iPSC-Ns in cell-replacement therapies relies on effective cryopreservation. In this study, we investigated the role of ice recrystallization inhibitors (IRIs) as novel cryoprotectants for iPSCs and terminally differentiated iPSC-Ns. We found that one class of IRIs, N-aryl-D-aldonamides (specifically 2FA), increased iPSC post-thaw viability and recovery with no adverse effect on iPSC pluripotency. While 2FA supplementation did not significantly improve iPSC-N cell post-thaw viability, we observed that 2FA cryopreserved iPSC-Ns re-established robust neuronal network activity and synaptic function much earlier compared to CS10 cryopreserved controls. The 2FA cryopreserved iPSC-Ns retained expression of key neuronal specific and terminally differentiated markers and displayed functional electrophysiological and neuropharmacological responses following treatment with neuroactive agonists and antagonists. We demonstrate how optimizing cryopreservation media formulations with IRIs represents a promising strategy to improve functional cryopreservation of iPSCs and post-mitotic iPSC-Ns, the latter of which have been challenging to achieve. Developing IRI enabling technologies to support an effective cryopreservation and an efficiently managed cryo-chain is fundamental to support the delivery of successful iPSC-derived therapies to the clinic.

Supercooling: A Promising Technique for Prolonged Organ Preservation in Solid Organ Transplantation, and Early Perspectives in Vascularized Composite Allografts

Ex-vivo preservation of transplanted organs is undergoing spectacular advances. Machine perfusion is now used in common practice for abdominal and thoracic organ transportation and preservation, and early results are in favor of substantially improved outcomes. It is based on decreasing ischemia-reperfusion phenomena by providing physiological or sub-physiological conditions until transplantation. Alternatively, supercooling techniques involving static preservation at negative temperatures while avoiding ice formation have shown encouraging results in solid organs. Here, the rationale is to decrease the organ's metabolism and need for oxygen and nutrients, allowing for extended preservation durations. The aim of this work is to review all advances of supercooling in transplantation, browsing the literature for each organ. A specific objective was also to study the initial evidence, the prospects, and potential applications of supercooling preservation in Vascularized Composite Allotransplantation (VCA). This complex entity needs a substantial effort to improve long-term outcomes, marked by chronic rejection. Improving preservation techniques is critical to ensure the favorable evolution of VCAs, and supercooling techniques could greatly participate in these advances.

Enhanced Cryopreservation Efficacies of Ice Recrystallization Inhibiting Nanogels

Development of new cryopreservation technologies holds significant potential to revolutionize the fields of cell culture, tissue engineering, assisted reproduction, and transfusion medicine. The current gold standard small-cell permeating cryopreservation agents (CPAs) demonstrate promising cryopreservation efficacies but are cytotoxic and immunogenic at the concentrations required for cryopreservation applications. In comparison, new cell impermeable CPAs of nanodimensions demonstrate outstanding potential to overcome the drawbacks of existing CPAs. In this study, we report the synthesis of vitamin B5 analogous methacrylamide (B5AMA)-incorporated nanogels as a potential solution to address the commonly observed limitations of existing CPAs. The stimuli-responsive poly(B5AMA) nanogels prepared by radical polymerization demonstrated significant ice recrystallization inhibition efficacies and showed either superior or comparable cryopreservation efficacies compared to the traditional cryoprotectant DMSO/glycerol in both eukaryotic and prokaryotic cells.